[FFmpeg-devel] DVB Subtitles

Reimar Döffinger Reimar.Doeffinger at gmx.de
Wed Dec 4 14:10:11 CET 2013

On Wed, Dec 04, 2013 at 12:26:15PM +0000, JULIAN GARDNER wrote:
> So as you see the canvas is being set to 1280x720 where as the subtitles are sized for a 720x576 screen.
> >>2013-12-04_11:44:10.28027 [mpegts @ 0x3231f80] sub2video: using 1280x720 canvas
> There is no DDS so the subtitles are draw in the top left corner and when overlayed over the live video are in the wrong place and small compared to the video.
> So my 1st idea is to change the way we set the canvas size, in this case it would be based on 720x576 as there is no DDS.

Unfortunately my experience from MPlayer is that this will most likely
break many streams.
I don't know whether that is a sample with or without DDS (nor if it
maybe specifies the size correctly in the stream properties), so it might
not quite demonstrate my point, but if you create any patch make sure it
will not break http://samples.mplayerhq.hu/sub/largeres_vobsub.mkv
Remuxing that one to MPEG-TS and checking it still plays correctly might
be a good idea, too.
I'll tell you if I manage to find any other samples.
But in principle the assumption of missing DDS -> use video size as
canvas size seems more reasonable to me than assuming it to be in SD
resolution (again, who creates HD content with SD subtitles? That must
look like crap).

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